docs: def purge_all(user=None, fast=False):
      """
      Remove all calculations of the given user
      """
      user = user or getpass.getuser()
      if os.path.exists(datadir):
          if fast:
              shutil.rmtree(datadir)
              print('Removed %s' % datadir)
          else:
              for fname in os.listdir(datadir):
                  mo = re.match('calc_(\d+)\.hdf5', fname)
                  if mo is not None:
                      calc_id = int(mo.group(1))
                      purge_one(calc_id, user)